/*
 * Copyright (C) 2007 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.android.dx.ssa;

import com.android.dx.rop.code.RegisterSpec;
import com.android.dx.rop.code.RegisterSpecList;

/**
 * Represents a mapping between two register numbering schemes. Subclasses of
 * this may be mutable, and as such the mapping provided is only valid for the
 * lifetime of the method call in which instances of this class are passed.
 */
public abstract class RegisterMapper {

	/**
	 * Gets the count of registers (really, the total register width, since
	 * category width is counted) in the new namespace.
	 * 
	 * @return >= 0 width of new namespace.
	 */
	public abstract int getNewRegisterCount();

	/**
	 * @param registerSpec
	 *            old register
	 * @return register in new space
	 */
	public abstract RegisterSpec map(RegisterSpec registerSpec);

	/**
	 * @param sources
	 *            old register list
	 * @return new mapped register list, or old if nothing has changed.
	 */
	public final RegisterSpecList map(RegisterSpecList sources) {
		int sz = sources.size();
		RegisterSpecList newSources = new RegisterSpecList(sz);

		for (int i = 0; i < sz; i++) {
			newSources.set(i, map(sources.get(i)));
		}

		newSources.setImmutable();

		// Return the old sources if nothing has changed.
		return newSources.equals(sources) ? sources : newSources;
	}
}
